Hydroponics is the practice of growing plants in a medium other than soil, using mixtures of essential plant nutrient elements dissolved in water. It is derived from two Greek words, “hydro” (water) and “ponos” (working), thus water-working. Hydroponics has been identified as the best technology for crop production, not only for urban and health-conscious societies, but also for land, labor and resource-scarce societies and remote communities around the world. Because of hydroponics, it is now technically feasible to obtain a fresh supply of vegetables, flowers, herbs, etc. on top of Mt. Everest, deep under the sea in submarines, in remote deserts, in drought prone areas and even in space stations.
Hydroponics was practiced in the BC in Egypt, China and India where ancient man used dissolved manure to grow cucumbers, watermelons and other vegetables in sandy river beds (aggregate hydroponics—sand culture). It was then referred to as Riverbed Cultivation. Later, when Plant Physiologists started to grow plants with specific nutrients for experimental purposes, they used the name nutri-culture. Then, terms like water culture, solution culture, and gravel bed culture etc. were mentioned. The chronology of events is given in Table 1. Though crop production has been practiced for centuries, serious work on the hydroponic methods of growing crops began only in the 1920s. The basics of commercial hydroponics were developed in the 1940s and marketed in the 1960s. Currently, there are numerous commercial hydroponic farms in many parts of the world. Apart from the government research institutions, many small and multinational companies in Australia, Belgium, Denmark, Holland, Japan, Taiwan and the U.S. have invested a lot in commercializing this technology. Horticulture, Plant Physiology and Hydroponics Labs around the world are working hard on refining this futuristic green technology. Now, hydroponics is the standard name for all cultivation methods that use nutrient solutions.
TABLE 1History of HydroponicsYearDevelopmentBCCompost/manure solution used to grow melons and othervegetables in the riverbeds during summer in Arabia, Babylon,China, Egypt, India and Persia1492Plants need mineral elements (Leonardo de Vinci - France)1666Plants grown in water in glass vials (Robert Boyle - Ireland)1699Nutrients absorbed by ion exchange (Woodword - England)1804Studies on crop nutrition (Nicolas de Saussure - France)1850Sand/quartz/charcoal culture (Jean Baussingault - France)1860Water/solution culture (Sachs and Knop - Germany)1920Formulating nutrient solution (Hoagland - USA)1940Nutriculture studies (Withers and Withers - USA)1945Nutrient film technique (Alan Cooper - UK)1960Aeroponics (Massantini - Italy).1970Floating hydroponics (Farnworth - USA)1975Raceways hydroponics - deep flow technique1980Many automated and computerized hydroponics farms establishedaround the world1990Home hydroponics kits gained popularity in Australia, Japan,Singapore and Taiwan
There are seven modern hydroponic techniques. In the Ebb and Flow Technique (EFT), as illustrated in FIG. 1, the nutrient solution is drained off 3-4 times a day to permit the roots to breathe. It is also called the “Flood and Drain Technique”, and is good for home gardens and nurseries. The second technique, illustrated in FIG. 2, is the “Deep Flow Technique” (DFT) where the depth of nutrient solution (several inches deep) is circulated around the roots by a pump and gravity drain. This method is also referred to as “Dynamic Root Floatation” or “Raceway Hydroponic” technique, and is ideal for leafy vegetables. FIG. 3 illustrates the technique known as the “Aerated Flow Technique” (AFT), a modified version of DFT. Here, the nutrient solution is profusely aerated by special mechanisms. Another technique similar to AFT is the Japanese “Kyowa Technique.” It is excellent for growing both leafy and fruit crops. The fourth technique, as illustrated in FIG. 4, is the “Nutrient Film Technique” (NFT), where a thin film of nutrient solution flows continuously down the sloped troughs to bathe the roots. FIG. 5 illustrates the “Drip Irrigation Technique” (DIT), where plants are grown in inert or organic substrates. The nutrient solution is fed closely around the roots 6-7 times a day in drops or trickles. Deserts in the Middle East are exporting crop production because of this technique. It is also suitable for plantation, orchard and landscaping industries. The sixth is the “Root Mist Technique” (RMT), illustrated in FIG. 6, where a mist of nutrient solution is sprayed constantly onto the roots of plants suspended from a frame in the top. This technique is known as “Aeroponics”. It is good for initiating rooting of cuttings and for providing optimum oxygen levels to the root zone. FIG. 7 illustrates the seventh technique, the Fog Feed Technique (FFT). It is similar to RMT but the droplet size is so minute that nutrient solution can barely moisten your hand. This technique has yet to be perfected. It is good for plants with aerial roots (i.e. orchids, anthuriums, etc.).
The main advantages of hydroponics include: higher crop yields; smaller space requirements; freedom from diseases; less labor; no weeding; higher growth rate; tendency to uniform results; and better control of pH and nutrient application. The main disadvantages include: high initial capital costs due to the use of tanks, pumps, lights, pipes, etc.; and high requirements for operational and technical skills.
All plants need 16 elements to grow—C, H, O, N, P, K, Ca, Mg, S, Zn, Cu, Fe, Mn, B, Mo and Cl. In nature, the plants derive these elements from the atmosphere or minerals in the soil. Most of the elements used in preparing nutrient solutions are derived from these naturally occurring minerals. Hydroponic aqueous solutions purity can be controlled unlike the soil culture that may contain impurities. There are numerous formulations of nutrient solutions available in the market. These formulations are based on the availability and price of the raw materials. Some are in solid form such as nutrient salts or fertilizers, some in liquid form and some in tablet form. Their composition depends on the raw materials and the intended purpose. Normally, nutrient solution for vegetative growth will have more nitrogen and less potassium and those for flowering and fruiting phase will have less nitrogen and more potassium.
Hydroponics is considered to be another technology to overcome food shortage in the future, especially in land, labor and resource scarce societies. It has the potential of being the best technology for certain photochemical from plant roots, especially by the pharmaceutical industries. When land, labor and natural resources become scarce and people look for healthy alternatives to farming and gardening, there is no choice but to turn to hydroponics.
Thus, there is a need for an irrigation system and method that provide an aqueous solution, which can include water and nutrients, to large and small fields alike.